Objective: As a member of Children's Cancer Study Group, the Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, New York, will continue investigations concerning the etiology, natural history, diagnosis and treatment of acute childhood leukemia and of solid tumors of children. Approach: The Department of Pediatrics is a participant in the activities of the Children's Cancer Study Group, which includes Dr. James A. Wolff, Dr. Anneliese L. Sitarz, Dr. Narayan R. Shah and Dr. William Speck and two Fellows. They attend all meetings of the Children's Cancer Study Group and participate actively in randomized trials related to the treatment of leukemia and solid tumors of childhood. They also participate in various ancillary studies conducted by the children's Cancer Study Group.